There is known a technology of shooting the scene of a city, a rural village or the like with a camera or the like, analyzing the shot image of the scene, and determining a ratio of green in the scene. Such a technology may be used as means of evaluating the scene in a greening plan or urban plan by the government or local authorities.
Moreover, Japanese Patent Application Laid Open NO. Hei 8-16789 discloses a method of determining the percentage of color in the scene in the image.    Patent document 1: Japanese Patent Application Laid Open NO. Hei 8-16789